Flexible supporting sheath for cables and the like

ABSTRACT

A universally articulable supporting sheath comprises an interconnected series of links, each having a convex spherical surface at one end, and a concave spherical surface at its opposite end. The concave and convex surfaces mate with one another to form the sheath. Special links having branch openings may be provided. Various forms of waterproofing seals are provided including O-rings, axially compressed rings, flexible belts, and ridges on the spherical surfaces. The links can be fitted together by thermal expansion. However, an axially split link is also described, which comprises two parts which snap together. The split parts may be molded as a unit with an integral thin wall hinge. The bending characteristics and bending radius of a sheath can be modified by insertion of spacers between the links at selected locations, or by the insertion of pins into radial holes provided in the links. Spacers with tongues may be used to prevent rotation of the links about the sheath axis, while allowing unidirectional articulation. Projections on one of a pair of mating spherical surfaces can be engaged with holes, slots or recesses of rectangular or other shapes to produce various limits on articulation and rotation. A single link may be provided with several alternatively usable holes, recesses and the like. The outer surface of a link can be provided with an axial extension engageable with a surface of an adjoining link to prevent back bending, or to prevent bending altogether.

CROSS-REFERENCE TO RELATED APPLICATION

This is a division of U.S. patent application Ser. No. 177,526, filed onApr. 4, 1988, which is a division of U.S. patent application Ser. No.849,029, filed Apr. 7, 1986, now U.S. Pat. No. 4,739,801, issued Apr.26, 1988.

BACKGROUND OF THE INVENTION

This invention relates to a flexible supporting sheath for cables, hosesand the like. It has particular utility where cables, hoses and the likeused for feeding electric power, control signals, gas water, oil, etc.are gathered in one or more groups, and supported and guided betweenmoving and fixed parts, or between moving parts, in a robot, or othermachine or machine tool.

In the conventional machine tool or the like, a flexible supportingsheath for cable or the like comprises a series of inner frames,adjacent frames being connected by surrounding pieces. The sheathencloses, supports and guides a portion of cable having a fixed end anda moving end, allowing the cable to be flexed repeatedly within aspecified range of movement. Each of the frames has two grooves ofspecified width arranged in uniformly spaced relationship, and thesurrounding pieces have flanges which fit into the grooves. Each of theinner frames in the sheath has surrounding pieces at both of its ends soas to make one united assembly.

Bellows-type sheaths have also been used to enclose cables and the likeconnected between relatively movable machine parts. Bundled cables havealso been used to make connections between relatively moving parts.

Although the conventional flexible supporting sheath, comprising framesand surrounding pieces, is capable of bending in a plane, and thusadapted for use with a linearly moving body, it is not suitable for usewith a robot capable of universal movement.

In the case of universal or three-dimensional movement, bellows orbundled cables have been used. However, with bundled cables, bunching ofthe cables may result in aesthetic problems in outer appearance, andfurthermore the cables may not be adequately protected. With sheaths ofthe bellows type it is difficult to cut and make connections.Furthermore, with bellows it is not possible to establish a specificminimum radius of curvature, and adequate strength for supporting thecables cannot ordinarily be attained.

In accordance with the present invention, a flexible supporting sheathfor cable and the like is formed by connecting hollow links in anarticulating chain characterized by interfitted inner spherical concavesurfaces and outer spherical convex surfaces. The links allow the sheathto be bent freely in any direction. The links include stop means forlimiting the articulation of joined links beyond a specified angle,thereby establishing a minimum bending radius.

In accordance with the invention, it is also possible to increase theminimum radius of curvature, and even to render portions of a sheathunbendable. This can be accomplished by the use of spacer membersinserted between adjoining links whereby bending is prohibited, orpartial bending is permitted so that the minimum bending radius isenlarged.

With the conventional supporting sheath consisting of alternated groovedframe elements and flanged connecting pieces, and even with abellows-type sheath, it was impossible to provide a branch in themidportion of the sheath. Branching is often desirable for makingelectrical or fluid connections in complex robots or machine tools.

In accordance with the invention, one or more of the links in theflexible sheath has at least three openings. Two of these openingsconnect respectively to adjacent links in the sheath, while a thirdopening connects to a branch. The branch can consist of a similararticulated sheath, in which case the third opening may have a sphericalfitting surface for connection to a first link of the branch.

Another aspect of the invention relates to preventing the intrusion ofwater and dust into the interior of the flexible sheath. This inventionsolves the problems of waterproofing and dust-proofing in a flexiblesupporting sheath by means of annular seals provided at the engagingparts of the concave and convex spherical surfaces, or by belt sealscovering the gaps between adjacent links, or by annular seals which arecompressed in these gaps, or by projections formed on the concave orconvex spherical surfaces which partially eliminate the gaps between theengaging spherical surfaces.

One problem with a flexible sheath in accordance with the invention isthat it is not necessarily easy to connect and disconnect a convexspherical surface and a concave spherical surface. This can be done byapplication of heat to the concave surface to cause it to expand.However a more effective means of connection and disconnection inaccordance with the invention is provided by splitting the links intohalves. Each of the halves is provided with two longitudinal faying, orclosely meeting, surfaces, and at least one pair of the faying surfacesare engaged to each other by snap-in connection.

To enable a flexible cable supporting sheath to follow a large varietyof movements and at the same time stabilize the paths of movement of thesheath, it is frequently necessary to provide a flexible sheath which isfixed at one part thereof, flexible in only one direction with a fixedminimum radius of bend at another part thereof and bendable to a fixedminimum radius in arbitrary directions at still another part thereof.Prior flexible sheaths have been unable to meet such requirements.

This invention satisfies these requirements by a construction in whicheach of the spherical surfaces is provided with one or more radialholes, and a pin is press fit in a hole in one link and loosely fittedin a hole in an adjacent link. The pin may be provided on a spacer whichis inserted in a gap between adjacent links. Alternatively, a spacerinserted in the gap between the adjacent links can have tonguesextending in the longitudinal direction and engaged with groovesprovided in the links to prevent the links from rotating.

Another way to meet the requirements for various motions such asone-dimensional, two-dimensional and three-dimensional motions inaccordance with the invention is to provide one of the sphericalsurfaces of a link with projections while the other is provided withrecesses. The projections are engaged with recesses.

By choosing the appropriate configurations for the projections andrecesses and, further, by providing the large diameter part on theoutside of the concave spherical surface with a stop projecting in thelongitudinal direction, it is possible to accommodate one-dimensional,two-dimensional, no-back-bend, three-dimensional and other motions,while increasing the slipping-off load of the links.

The invention has the following objects:

(1) To provide a flexible supporting sheath for cables and the likewhich can be smoothly bent in any direction, so that it may easilyfollow the movable parts of robots and other automatic machines.

(2) To accommodate all movements of factory automation equipmentdesigned for unmanned operation in the factory in response to the needsof recent industrial technology, and to make improved utilization of theflexible supporting sheaths for cables and the like.

(3) To provide a closed and dust-proof sheath structure which isresistant to the entry of foreign materials from outside the structureand in which the cables, hose and the like within the sheath areprotected in a superior manner.

(4) To conceal the cables, hoses and the like from view and to provide asheath having an aesthetically pleasing outer appearance.

(5) To provide a flexible supporting sheath having a predeterminedminimum bending radius.

(6) To provide a flexible supporting sheath in which internal cables,hoses and the like are stored in a compact form.

(7) To provide a flexible supporting sheath which is light in weight anddoes not generate sound when used.

(8) To provide a flexible supporting sheath having a minimum number ofdifferent component parts so that it can be economically mass-produced.

(9) To provide a flexible supporting sheath in which the links caneasily be connected and their assembly can easily be performed, and thelength of which can be changed easily by adding or removing links.

(10) To provide for various operating conditions by the choice ofthickness, shape, inserting position and the like, of spacers insertedbetween the links.

(11) To produce a compact installation of the sheath, improve its outerappearance and increases the safety of operation by using spacersbetween links to restrict the movement of the sheath.

(12) To facilitate adjustment, restrict the movement of, and stabilizethe sheath unit while its entire movement is being confirmed, by theinsertion or removal of spacers on site.

(13) To make fluid or electrical connections between one stationary ormovable part and a plurality of movable parts, or between one movablepart and a plurality of stationary or movable parts, while maintainingelectrical and fluid conductors in a compact form.

(14) To increase the lateral rigidity of a flexible connection byproviding multiple interconnected parallel sheaths.

(15) To accommodate a wide variety of multiple-branch applications byproviding links of various shapes such as L-shape, T-shape, Y-shape,cross-shape and others.

(16) To provide additional support for a flexible supporting sheath byutilizing a branched part of the sheath to support part of the sheath bysuspending it, for example, from the main body of a machine.

(17) To provide a flexible multiple-link supporting sheath having animproved sealing structure resistant to penetration of cutting coolants,water, oils or the like from the exterior, while maintaining the featureof the flexible sheath that it can be three-dimensionally bent inarbitrary directions.

(18) To make it easy to make connections of a sheath to fixed or movablemachine element on site.

(19) To make it possible to remove and replace individual linksconveniently in making repairs or adjustments.

(20) To make it easy to make connections of a sheath to fixed or movablemachine element on site.

(21) To provide for simpler and more economical manufacture of moldedlinks by utilizing a split link structure, thereby making it easier toeject the link parts from the mold and increasing the useful life of themold.

(22) To provide for increased slipping-off load in a flexiblemultiple-link sheath having spherical mating elements, and to make itpossible to mold link elements of various different designseconomically.

(23) To limit the directions in which the links of a flexible supportingsheath can be articulated by means of insertable pins or speciallyshaped spacers, thereby insuring stability of the sheath and restrictingits path of movement, as required under various operating conditions.

(24) To increase the tensile strength of the sheath by means of insertedpins.

(25) To limit the freedom of movement of articulating links in variousways by means of interengaging pins and slots or grooves so thatdifferent sheath characteristics can be achieved by constructing a cablefrom a series of identical links, or from a series of links some ofwhich are different from the others.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view showing a conventional flexible supportingsheath for cables and the like;

FIG. 2 is an axial section through a part of the sheath of FIG. 1;

FIG. 3 is a schematic view showing a typical application of the flexiblesupporting sheath of FIG. 1;

FIG. 4 is an elevational view showing a first embodiment of theinvention;

FIG. 5 is an axial section through part of the sheath of FIG. 4;

FIG. 6 is an axial section showing a second embodiment of the invention;

FIG. 7 is an axial section showing a third embodiment of the inventionin which spacers are used to limit articulation of the links of thesheath;

FIG. 8A is a perspective view showing one form of spacer usable in theembodiment of FIG. 7;

FIG. 8B is a perspective view showing another form of spacer usable inthe embodiment of FIG. 7;

FIG. 9 is a schematic view of a sheath connected between two relativelymovable machine elements, in which spacers are used to limitarticulation of parts of the sheath;

FIG. 10 is an elevational view showing an embodiment of the invention inwhich the sheath is branched;

FIG. 11 is an axial section showing details of the branching link ofFIG. 10;

FIG. 12 is an axial section showing details of an alternative branchedsheath;

FIG. 13 is an axial section showing details of a further alternativebranched sheath;

FIG. 14 is a front elevational view for showing a pair of supportingsheaths extending in parallel and interconnected by branches;

FIG. 15 is a side elevation of the sheaths of FIG. 14;

FIGS. 16 through 20 are fragmentary side elevations, partly in section,showing several alternative forms of seals for the interconnectedspherical surfaces of links in accordance with the invention;

FIGS. 21A-21F are respectively a front elevation, right side elevation,left side elevation, top plan, bottom plan and rear elevation of onehalf of an axially split link consisting of two identical parts;

FIG. 22 is a front elevation showing, in assembled condition, a linkconsisting of two of the halves as shown in FIGS. 21A-21F;

FIGS. 23A-23F are respectively a front elevation, right side elevation,left side elevation, top plan, bottom plan and rear elevation of onehalf of an alternative axially split link consisting of two identicalparts;

FIG. 24 is a front elevation showing, in assembled condition, a linkconsisting of two of the halves as shown in FIGS. 23A-23F;

FIGS. 25A-25F are respectively a front elevation, right side elevation,left side elevation, top plan, bottom plan and rear elevation of anaxially split link consisting of two parts connected by a hinge;

FIG. 26 is a front elevation showing the split link of FIGS. 25A-25F inassembled condition;

FIGS. 27A-27F are respectively a front elevation, right side elevation,left side elevation, top plan, bottom plan and rear elevation of analternative axially split link consisting of two parts connected by ahinge;

FIG. 28 is a front elevation showing the split link of FIGS. 27A-27F inassembled condition;

FIG. 29 is an exploded perspective view of an alternative form of linkelement in accordance with the invention having articulation restrainingpins cooperating with transverse holes bored through the sphericalmating surfaces of the link element;

FIG. 30 is a side elevation of a portion of a sheath made up of links ofthe type shown in FIG. 29;

FIG. 31 is an axial section through the sheath of FIG. 30;

FIG. 32 is a side elevation of a sheath in accordance with the inventionhaving articulation restraining spacers;

FIG. 33 is an axial section through the sheath of FIG. 32;

FIG. 34 is a side elevation of a section of sheath in accordance withthe invention using another form of articulation restraining spacer;

FIG. 35 is an axial section through the sheath of FIG. 34;

FIG. 36 is a perspective view of one form of articulation restrainingspacer;

FIG. 37 is a perspective view of another form of articulationrestraining spacer;

FIG. 38 is a top plan view of a sheath in accordance with the inventionhaving still another form of articulation restraining spacer;

FIG. 39 is a front elevation, partly in section, of the sheath of FIG.38;

FIG. 40 is a perspective of one form of articulation restraining spacer,as used in the sheath of FIGS. 38 and 39;

FIG. 41 is a perspective view of another form of articulationrestraining spacer as used in FIGS. 38 and 39;

FIG. 42 s a top plan view of another sheath in accordance with theinvention having articulation restraining spacers;

FIG. 43 is a side elevation, partly in section, showing the sheath ofFIG. 42;

FIG. 44 is a perspective view of one form of articulation restrainingspacer as used in the sheath of FIGS. 42 and 43;

FIG. 45 is a perspective view of another form of articulationrestraining spacer as used in the sheath of FIGS. 42 and 43;

FIG. 46 is an elevational view of a portion of a sheath in accordancewith the invention, in which the convex spherical surfaces of the linkshave recesses;

FIGS. 47A and 47B are respectively front and right side elevationalviews of one link of the sheath of FIG. 46;

FIG. 48 is an elevational view of a sheath in accordance with theinvention in which the convex spherical link surfaces are provided withrecesses, while the concave spherical surfaces have projections;

FIGS. 49A, 49B and 49C are respectively front, right side and left sideelevational views of a link from the sheath of FIG. 48;

FIG. 50 is an elevation of a portion of a sheath in accordance with theinvention in which the links have projections and recesses as in FIG.48, and in which the links also have stopping surfaces for preventingreverse bending of the sheath;

FIGS. 51A, 51B and 51C are respectively front, right side and left sideelevational views of the sheath of FIG. 50;

FIG. 52 is an elevational view of a portion of a sheath in accordancewith the invention which is non-articulating, but which is can be matedwith articulating links;.

FIGS. 53A and 53B are respectively front elevational and right sideelevational views of a link from the sheath of FIG. 52;

FIG. 54 is an elevational view of another embodiment of a sheath inaccordance with the invention in which the concave spherical surfaceshave inward projections, and in which the convex spherical surfaces haverectangular slots permitting both limited articulation and rotation;

FIGS. 55A, 55B and 55C are respectively front, right side and left sideelevational views of a link from the sheath of FIG. 54;

FIG. 56 is an elevational view of a sheath in accordance with theinvention in which the concave spherical surfaces have inwardprojections, and in which the convex spherical surfaces have elongatedarticulation limiting slots;

FIGS. 57A, 57B and 57C are respectively front, right side and left sideelevational views of a link from the sheath of FIG. 56;

FIG. 58 is an elevational view of a sheath in which the concavespherical surfaces have inward projections, and in which the convexspherical surfaces have elongated slots positioned to allow twodimensional articulation, but to prevent reverse bending;

FIGS. 59A, 59B and 59C are respectively front, right side and left sideelevations of a link from the sheath of FIG. 58;

FIG. 60 is an elevational view of a portion of a sheath in accordancewith the invention in which the concave spherical surfaces have inwardprojections mating with recesses in the convex spherical surfaces insuch a way as to prevent articulation altogether;

FIGS. 61A, 61B and 61C are respectively front, right side and left sideelevations of a link from the sheath of FIG. 60;

FIGS. 62A, 62B, 62C, 62D and 62E are respectively front, right side andleft side elevations, top and bottom plan views of a link in which theconcave spherical surface has opposed inward projections, and in whichthe convex spherical surface has a plurality of alternatively usablerecesses of different shapes;

FIGS. 63A and 63B are enlarged schematic views showing additionaldetails of a typical projection and recess respectively;

FIG. 64 is a schematic view showing the relationship between arectangular recess and a projection;

FIG. 65 is a schematic view showing the relationship between anelongated recess and a projection;

FIG. 66 is a schematic view showing the relationships between theelongated recesses and projections of the links in FIG. 58, in whichreverse bending is prevented; and

FIG. 67 is a fragmentary elevational view of a link having a complexform of slot.

DETAILED DESCRIPTION

The conventional flexible supporting sheath, as shown in FIGS. 1 and 2,comprises a series of hollow inner frames 2, adjacent frames beingconnected by surrounding pieces 3. The sheath encloses, supports andguides a cable 4 having a fixed end and a moving end, allowing the cableto be flexed repeatedly within a specified range of movement. Each offrames 2 has two grooves of specified width arranged in uniformly spacedrelationship. The surrounding pieces 3 have flanges which fit into thegrooves. Each of the inner frames in the sheath has surrounding piecesat both of its ends so as to make one united assembly. Coupling elementsare connected to the surrounding pieces at the ends of the sheath forconnecting the ends of the sheath to relatively movable machine parts.

The conventional flexible supporting sheath of FIGS. 1 and 2 is capableof bending in a plane, and thus adapted for use with a linearly movingbody as in FIG. 3. It is not suitable for use, however, with a robotcapable of universal movement.

The sheath of the present invention is characterized by interfittedinner spherical concave surfaces and outer spherical convex surfaces.Various provisions may be made in accordance with the invention forrestricting articulation of the links. However, unless such restrictingprovisions are present, the links allow the sheath to be bent freely inany direction within a limited range. The links themselves include stopmeans for limiting the articulation of joined links beyond a specifiedangle, thereby establishing a minimum bending radius.

When one of the links reaches a bending limit relative to an adjacentlink, a next link in the series bends in sequence, resulting in theformation of a specified bending radius. Since each of the links in theseries can be bent in any direction, the sheath may be bent in a threedimensional pattern while the specified bending radius is maintained.

A spacer may be inserted into spacers between the links of the sheathwhere bending is not required.

In FIGS. 4 and 5 a flexible supporting sheath 5 comprises a series ofinterfitted hollow links 6, having spherical convex and concave surfacesat their right and left ends respectively. The ends of the supportingsheath 5 are provided respectively with flanged couplings 7 and 8.Coupling 7 has a spherical convex surface, while flange 8 has aspherical concave surface.

Link 6 has an offset shape in which an inner spherical concave surface10 is formed within a cylinder 9 at its large diameter end, and in whicha projection 12 of smaller diameter has an outer spherical convexsurface 11. The link has a longitudinal cylindrical hole 13 having asmaller diameter than that of each of said spherical surfaces. Each ofthe links is inserted into an adjoining link by engagement of theirspherical concave and convex surfaces. Each of the links is fitted toits adjoining link so that they can articulate smoothly through an angleθ from aligned relationship with an adjoining link. When one link isrotated through an angle θ from an aligned relationship with an adjacentlink, contact takes place at surface 14 or at surface 15. These surfacesserve as stop surfaces to limit articulation of adjoining links to amaximum angle θ.

The inner surfaces of links 6 are finished smoothly so as not to damagethe cable 4, hose or the like extending through the sheath. For the samereason the corners capable of contacting the cable are chamfered. As therelatively movable machine elements connected by the sheath are moved,and each link 6 is rotated through an angle θ, the adjoining link 6 isrotated in sequence. The sheath therefore bends to a specified bendingradius. Since each of the links 6 can be rotated through an angle θ inany direction at its spherical surface, it is possible to bend thesheath in a three-dimensional manner while maintaining a specifiedbending radius.

As shown in FIG. 5, the interior of projection 12 is generallycylindrical, although its diameter is gradually reduced where it meetsthe intermediate portion of the passage which connects the convex andconcave parts. Similarly, the intermediate portion of the passage iscylindrical, except for the chamfered surface, where it meets theconcave inner surface of the link. The diameter of the opening of theend portion of the internal passage of the link at the end of projection12 is greater than the minimum diameter of the intermediate portion ofthe link. Preferably, the diameter of the opening in projection 12 isgreater than the minimum diameter of the intermediate portion of thepassage by an amount such that, when two joined identical links are bentrelative to each other to the limit of their articulation, the end ofthe convex projection does not extend inwardly, beyond the intermediateportion of the adjacent link, into the continuous hollow passage formedby the links. As shown in FIG. 5, even when the sheath is articulated toits limit, there is no stepped portion in the sheath which would impartshear or tension to the cable inside the sheath. When the left hand linkis bent downwardly, the end of its externally convex projection does notcause the cable to move relative to the other links, because it does notextend into the continuous hollow passage beyond the cylindrical innersurface of the intermediate portion of the middle link. Thus, even underconditions of repeated bending of the sheath, adverse effects on thecable are avoided.

In the embodiment of FIG. 5, for example, the diameter of the internalpassage within projection 12 can be 21 mm. while the diameter of theintermediate passage can be 18 mm.

One way to connect the links to each other is by thermal expansion. Toconnect links 6 to each other, their spherical concave surfaces areimmersed in water at a temperature preferably from 70° C. to 100° C. toproduce a local expansion of the diameter of the concave surface. Thespherical convex part of the adjoining link is then inserted into theconcave part and the concave part is allowed to contract.

In the second embodiment of the invention, as shown in FIG. 6, aflexible supporting sheath 16 comprises articulating links, each linkcomprising a pair of outer and inner link elements. Hollow outer linkelements 18, having inner spherical concave surfaces 17 at both ends,and hollow inner link elements 20, having spherical convex surfaces 19at both ends are connected alternately. The inner link element 20 has acentral ring-like projection 21, serving as a stop for limiting arotation of the right and left adjoining outer link elements 18 to aspecified angle. The convex and concave surfaces are fitted to eachother so that, when the flexible supporting sheath 16 is bent, each ofthe link elements articulates smoothly relative to its adjoining linkelements. When the link element is rotated through a specified anglerelative to an adjacent link element, contact takes place at surface 22,or at surface 23, or at both surfaces, to limit articulation of the linkelements. The inner cylindrical surfaces of the inner link element 20and of the outer link element 18 are finished smoothly and cornerscapable of contacting the cable are chamfered so as not to cause damageto the cable.

In FIG. 7 a ring-like spacer 24 is inserted into a flexible supportingsheath 5' and the like comprising a series of interconnected offset-typelinks.

When it is desired to prohibit the bending of the flexible sheath 5', aspacer 25 as shown in FIG. 8A is inserted into the end part of thespherical convex surface 11 of the link 6. Of course, the insertingpoint may be an end part of the spherical concave surface 10 of theadjoining link 6.

When it is desired to modify the bending radius of the flexiblesupporting means 5' of the preferred embodiment, an appropriatethickness for spacer 25 is selected, or only one spacer is inserted forevery several links. Further, when it is desired to maintain and fix aspecified bending radius, a tapered spacer 26 as shown in FIG. 8B may beused.

FIG. 9 shows a sheath in which spacers are inserted at portion 29 of thesheath near the fixed machine part 27 and at portion 30 of the sheathnear the moving part 28 of the machine. Only the central part 31 of thesheath bends. The moving machine part 28 can move in any direction. Theflexible supporting sheath 5' is partially restricted against bendingboth ends. This limits the bending of the sheath, and is one way toprevent reverse bending.

The embodiment of the invention shown in FIGS. 10 and 11 comprises abranched sheath 32. The sheath, for the most part, comprisesconventional links 33 similar to those depicted in FIGS. 4 and 5.Flanged couplings 34 and 35 are similar to coupling 8 in FIG. 4. Flangedcoupling 36 is similar to coupling 7 in FIG. 4. A T-shaped link 37,inserted along the main section of the sheath, allows the connection ofa branch to an intermediate location on the main section.

The T-shaped link 37, as shown in FIG. 11, has three openings, onehaving a spherical concave surface, and the other two having sphericalconvex surfaces. The concave surface 38 fits the convex surface 39 ofadjoining link 33 in such a way as to allow articulation of links 33 and37 in the same manner as described with reference to FIGS. 4 and 5.Convex surfaces 40 and 41 fit concave surfaces of links of main sheathsection and branch respectively.

The flexible supporting sheath of this embodiment can be branched at anylocation by means of the T-shaped link 37, and at the same time it maybe bent in any direction.

FIG. 12 shows an embodiment of the present invention which has adivisible Y-shaped link 42 connected to links 43 and 44 of a main sheathsection. A branch can be connected to convex spherical part 45.

FIG. 13 shows an embodiment of the invention which has a multi-directedbranch link 46 connectable to a large diameter link 47 and to severalsmaller diameter links 48, 49 and 50, each of which is a first link in aseparate branch.

FIGS. 14 and 15 show an embodiment of the invention in which twoparallel sheaths 51 and 52 are interconnected at flexible supportingmean for cable and the like to have one or more locations by means of Tor L-shaped links 53 and 54.

The links of the sheath may be provided with one or more of a pluralityof alternative sealing structures as depicted in FIGS. 16-20.

FIG. 16 shows a sealing structure wherein, of a concave sphericalsurface 56 and a convex spherical surface 57, the convex sphericalsurface is provided with a groove 58, in which an annular 0-ring seal 59is placed.

FIG. 17 shows a sealing structure which is similar to that shown in FIG.16 except that projecting ribs 61 and 62 are provided on both sides ofthe annular seal 63 to prevent the seal 63 from slipping off thespherical surface when the links are articulated. In addition, awaterproofing effect is achieved by the projecting ribs.

FIG. 18 shows a sealing structure in which a flexible belt seal 65 isexternally fitted to the gap formed between the links thereby providinga waterproofing effect. The belt is provided with ribs 67 and 68, whichfit into grooves formed in the outer surface of the links.

Next, FIG. 19 shows a sealing structure in which flexible annular seals70 and 71 are fitted respectively into the outer and inner gaps formedbetween the links in the axial direction, resulting in a waterproofstructure. These annular seals can be used together or alternatively.They are inserted at the time the links are connected together. If theseal is compressed when it is installed, a sealing effect can beachieved even when the sheath is articulated, provided that the degreeof bending of the links is not too great.

Finally, FIG. 20 shows a sealing structure not using flexible seals, inwhich annular rib-like projections 73 and 74 are provided on the convexspherical surface 75 and are closely fitted to the concave sphericalsurface 76, thereby reducing the area of contact of the concave andconvex spherical surfaces to permit smooth articulation while achievinga waterproof structure. In this case, the gap is set to be substantiallyzero. A close fit is insured, preventing penetration of water or thelike from the exterior. The annular projections instead of being on theconvex spherical surface, may be provided on the concave sphericalsurface 76.

The shapes of the links shown in FIGS. 16-20 are merely specifiedexamples, and a variety of modifications can be made, as described withreference to the other embodiments mentioned above.

The need for immersion of the concave parts of the links in hot waterduring assembly can be avoided by the adoption of one of the structuresdepicted in FIGS. 21A-28.

First, FIGS. 21A-F and 22 illustrate a link consisting of two identicalhalves 78 and 78'.

The half link 78 has longitudinal faying surfaces 80 and 81 seen in FIG.21E. For engagement of the larger diameter parts, faying surface 80 hasa tongue 82 projecting in the circumferential direction, while surface81 has a recessed groove 83 to engage with the tongue of a mating halflink. On the small diameter part, surface 80 has a projection 84, whilesurface 81 has a recessed groove 85. Two half links are arranged to faceeach other, and snapped together, as shown in FIG. 22. FIG. 22 showstongue 82 fitting into recessed groove 83'.

The coupled half links can be easily disconnected by inserting the tipof a screwdriver into a groove 83', disconnecting tongue 82 from groove83', and forcing the links apart.

FIGS. 23A-F and 24 show another example of identical link halves whichsnap together.

In this example, snap-in type connection is accomplished by ball-likeprojections 86 and holes 87. In other respects, the structure of thelink is the same as that in FIGS. 21A-F. Disconnection of the coupledhalf links is effected by inserting a screwdriver in a groove 88 andturning to force the links apart.

The couplings 7 and 8 in FIG. 4 can be embodied in split form, all theirhalves can be connected together by balls and holes in a manner similarto what is depicted in FIG. 24.

Next, FIGS. 25A-F and 26 show a unitary link formed by integrallymolding two half links similar to those shown in FIGS. 21A-F and 22.

In this structure, the half links 90 and 91, as shown in FIG. 25B, areconnected by a bendable, integrally molded, thin wall hinge 92. Thelarge diameter part of the half link 90 has a tongue 93 while half link91 has only a recessed groove 94. The small diameter parts haveengageable tongues 95 and grooves 96 similar to those in FIGS. 21C and21E.

FIGS. 27A-F and 28 show a link structure in which two half links areintegrally molded together through a thin wall hinge 98. The fayingsurfaces are engaged to each other through projections 99 and holes 100in the same manner as in FIG. 24. Again, a slot 101 is provided forinsertion of a screwdriver or similar prying tool to disconnect the twolink halves.

The specific shapes of the links shown above are mere examples, andmodifications can be made, for example as shown in the other examples.Various alternative snap connections can be used.

FIG. 29 shows a link element 102 and pins 103 for interconnecting thelinks. Link element 102 has an inner concave spherical surface 104 (FIG.31) on one end and an outer convex spherical surface 105 on the otherend. Radial holes 106 and 107 are arranged symmetrically in vertical andhorizontal directions intersecting the centerline of the link. There maybe more or fewer of such holes, but in the case shown, there are fourholes in the convex part of the link and four holes in the concave part.

FIGS. 30 and 31 show the condition wherein the pins 103 are insertedinto interconnected links 102.

The pins 103 are press fit tightly in the holes of the larger diameterparts 108 of the links and fit loosely in holes in the smaller diameterpart 109.

The lengths of the pins 103 are such that the pins do not protrude fromthe inside surfaces of the smaller diameter parts 109.

When the pins 103 are engaged with an adjacent pair of links at all fourlocations, the links 103 cannot be articulated and are self-supporting.

When the pins 103 are engaged with an adjacent pair of links at twosymmetrically opposed locations, the links can be articulated in onlyone direction, so that a flexible sheath capable of two-dimensionalmovement is realized. In this case, since the pins are located on thebending axis, smooth articulation takes place. The tensile load of thelinks is also increased. Of course, the joint is flexible in alldirections where no pin 103 is inserted. Using links with holes as shownin FIG. 29, a given sheath can be constructed with a wide variety ofbending characteristics by an appropriate choice of pins.

The links may be configured with stop surfaces so that a gap w as shownin FIG. 2 remains even when the adjacent links are bent to the maximumdegree. This way the possible nipping of a finger, or damaging a machinepart, tool or the like by pinching, can be avoided.

FIGS. 32 and 33 show a sheath wherein the links 111 have arcuate spacers112 and 113. As shown in FIG. 36 spacer 112 has a gap in itscircumference, and has arms with opposed inwardly extending pins 114.These pins extend into radial holes in the mating spherical parts andhelp to hold the links together.

The spacer 112 is for use in the case where the links are to be securedtogether in a line.

The spacer 113 is a tapered link for use in the case where links are tobe secured together at a fixed radius of curvature.

FIGS. 34 and 35 show links 115 having spacers 116 semi-arcuate in shapeand having opposed inwardly extending pins 117, a perspective view ofthe spacer 35 being shown in FIG. 37.

With the spacers 35 inserted, a flexible support incapable of reversebending is achieved. That is, the links can be bent in one direction butnot in the opposite direction.

Since the pins 117 are inserted in the holes of the larger diameter part118 as shown in FIG. 34 the spacer 116 moves together with the link andalong the spherical outer surface of a small diameter part 119 when thelinks are bent.

The spacer of FIG. 37 has both a stopping function and a pin function,can be easily inserted into the link, and can be set at any chosenlocation along a sheath where the reinforcing property of the pins orthe restricting property of the spacer is desired. The spacer 116 isloosely fitted to the outer spherical surface of the small diameter partand the adjacent links are interconnected by pins 117, so that thestrength of the flexible sheath is increased.

When the width of the spacers shown in FIGS. 36 and 37 is varied or thespacers are tapered, structures capable of maintaining various radii ofbending can be obtained.

In FIGS. 38 and 39 spacers 122 and 123 shown in FIGS. 40 and 41 areengaged, respectively in a sheath.

Pins 124 shown in FIG. 38 are engaged on both sides of each link, andthe link element is provided in its outside surface with one or moregrooves 125 into which a tongue 126 or 127, provided on the spacer, ispress fit and fastened. Each of the spacers 122 and 123 is provided onits one side with the tongue conforming to groove 125, and is fastenedby press fitting or snap connection of the tongue and the link element.

Although in the above description pins 124 are required in the case oftwo-dimensional bending, pins 124 may be omitted where other means forpreventing relative rotation of the adjacent links is provided. Such ameans is shown in FIGS. 42 to 45.

Spacers 130 and 131 are each provided with tongues on both sides of thecircumference thereof. In the case of spacer 130, tongue 135 engages agroove 136 while tongue 137 engages a groove 138. The spacer holds thetwo adjacent links against articulation, while the tongues preventrelative rotation of the links about the axis of the sheath.

Tongue 132 of spacer 131 is tightly fitted (e.g. snap-connected) to thelink body, and is fastened to the link. On the other hand, tongue 133has a length sufficient to permit the concave spherical inner surface ofthe mating link to move to a maximum bending angle. Tongue 133 isengaged with, and capable of smoothly moving in, a groove 134 cut out inthe mating link. With this construction, the links are prevented fromrotating relative to each other, and with spacers 131 in use, theflexible sheath can be bent only in a two-dimensional manner and withoutback bending.

The structure shown in FIGS. 29-45 provides a flexible support capableof stably following up any kind of movement by using basic common linkswhile making various modifications in the performance of the links bymeans of pins or spacers which are engaged to the links. For theflexible sheath as a whole, a construction permitting non-dimensional,two-dimensional or three-dimensional movement can be freely selected atany desired position along the length of the sheath, and the sheath canbe flexibly adapted to the robot on other machine with which it is to beused.

The shape of the links shown in FIGS. 29-45 is merely an example, and avariety of modifications can be made, such as described above withreference to other examples.

When links 140, shown in FIGS. 46, 47A and 47B, are interconnected, thelinks can be articulated three-dimensionally in arbitrary directions tothe extent of a fixed minimum bending radius. In addition, the links canbe rotated relative to each other.

The link 140 is provided with an opposed pair of recesses 141 in aconvex spherical surface 142, for engagement with any of a variety oflinks shown in FIGS. 48-53B.

When the links 143 shown in FIGS. 48, 49A, 49B and 49C areinterconnected, the links can be articulated in one direction, and thesheath is two-dimensionally flexible in the vertical direction as viewedin FIG. 48 to a fixed bending radius. Bending takes place on an axisthrough the center of the mating concave and convex spherical surfaces.Links cannot be rotated relative to each other.

Each link 143 is provided with an opposed pair of projections 145located along a line through the central axis if the link on concavespherical surface 147. Each link also has an opposed pair of recesses148 at symmetrical positions along a line through the central axis ofthe link on convex spherical surface 149. When the links 56 areinterconnected, the projections 145 are loosely fitted in the recesses148. The diameters of the projections 145 are small enough, as comparedwith the diameters of the recesses 148, to permit easy bending, and thetip of each projection is so sized as to touch the mating convexspherical surface lightly.

As for the head profile of projection 145, as shown in FIG. 63A, thehead is chamfered at 150 in a tapered form on the insertion side overabout one-half the width of the projection, to produce a semi-circularchamfered surface. On the other hand, the recess 148 is provided with atapered guide surface 152 for insuring easy guiding of projection 145from the end face to the recess, as shown in FIG. 63B. This structurefacilitates the insertion of the projection and the connection of thelinks.

When links 154 shown in FIGS. 50, 51A, 51B and 51C are interconnected,the links can be bent in one direction on an opposed pair of projections155 at the bending axis, but cannot be bent in the opposite direction.The links 66 cannot be rotated relative to each other.

Link 154 differs from link 143 in that the large diameter part 157 oflink 154 has a stop 158 projecting in the longitudinal direction forinhibiting bending between the links. Stop 158 extends over acircumferential angular range of about 180° and produces a "no backbend" structure in which bending in one direction is permitted, butbending in the opposite direction is prevented. By changing the width ofthe stop 158, a structure capable of allowing back bend having anydesired limit can be obtained.

In the other structural respects, the link 154 is the same as the link143.

When links 160 shown in FIGS. 52, 53A and 53B are interconnected, asheath section not bendable in any direction can be obtained.

As compared to the link 158, link 160 may be described as one in which astop 162 projecting in the longitudinal direction is provided over theentire circumference of the large diameter part 164 whereby no gap isleft between the adjacent links. Recesses 166 are provided forengagement with the projections of other links.

Links 140, 143, 154 and 160 may be interconnected in desiredcombinations to stabilize the moving paths of the sheath so produced topermit three-dimensional motion and rotation and to achieve variousdesirable sheath characteristics.

FIGS. 54 to 62E show assembly views and elemental views of linksconstituting another group of examples of the invention.

When links 167 shown in FIGS. 54, 55A, 55B and 55C are interconnected,the links can be bent to a fixed radius of bend in an arbitrarydirection.

The adjacent links 167 can be rotated about the sheath axis to alimiting angle θ relative to each other, so that the number of linksrequired for a 360° rotation of the entire body of interconnected linksis 360/θ°.

The concave spherical surface 169 is provided at its inner part with anopposed pair of projections 170 at positions angularly shifted 90° fromthe bending axis, while the convex spherical surface 172 is provided atits outer surface with substantially rectangular recesses 173.

The action obtained through the engagement of projection 170 and therecess 173 is explained by referring to FIG. 64 as follows: when theprojection 170 makes a movement from a to b, the links are bent throughan angle α° (see FIG. 54).

In addition, when the projection 170 makes a movement from c to d or eto f in the recess 173, each link can perform a rotation through anangle θ (see FIG. 55B).

When links 180 shown in FIGS. 56, 57A, 57B and 57C are interconnected,the links can be bent in one direction (the vertical direction in FIG.11) to a fixed bending radius but the links cannot be rotated relativeto each other.

The link 180 is provided, at an outer part of its convex sphericalsurface 182, with a pair of recesses in the form of slots 183 atsymmetrical positions such that the recesses 183 can be engaged withsymmetrically opposed projections 185. As shown in FIG. 56 and 65, whenthe projection 185 makes a movement from a to b in the mating recess,the links can be bent through an angle α.

Link 180 differs from the link 167 in the shape of the recesses.

When links 190 shown in FIGS. 58, 59A, 59B and 59C are interconnected,the resultant link body has a "no-back-bend" structure which can be bentin one direction but not in the opposite direction.

One of a pair of recesses 191 is a slot extending to the left from aneutral line, while the other is a slot extending to the right from theneutral line. When a pair of projections 192 make a movement from a tob, as shown in FIG. 66, the links 190 can be bent to a predeterminedlimiting angle relative to each other. The lengths L₁ and L₂ are equal,but by varying the length, any desired bending fixed radius limit can beachieved. Link 190 differs from the links 167 and 180, only in the shapeand location of the recesses.

When links 192 shown in FIGS. 60, 61A, 61B and 61C are interconnected, anon-bendable, self-supporting sheath section is formed.

Concave spherical surface 194 is provided at two pairs of opposedprojections 196. Convex spherical surface 197 is provided at its outerpart with four round recesses 198 at positions suitable for engagementwith the projections 196. (Of course, three, or more than fourprojections and a corresponding number of recesses can be provided.)

When the links 192 are interconnected, the four projections and the fourround recesses are snugly engaged to each other, so that the linkscannot be moved in the longitudinal or the transverse direction relativeto each other, and a self-supporting property is achieved.

Projections on link 192 are removed by cutting or the like while leavingone opposed pair of projections, so that link 192 can be coupled to alink corresponding to links 167, 180 or 190.

To facilitate insertion of the projections into the recesses, links 160,167, 180 or 192 mentioned above can be provided with the same insertionfacilitating structure as shown in FIGS. 63A and 63B.

FIGS. 62A, 62B, 62C, 62D and 62E show a link 200 which has all thecharacteristic features of links 167, 180, 190 and 192.

This link is characterized in that the same basic link can be used invarious ways for one-dimensional, two-dimensional and three-dimensionalmotions.

Four pairs of opposed recesses are provided on the convex sphericalsurface. The shapes of recesses are different for different pairs.

Round holes 202 are provided for one-dimensional use. Slots 204 areprovided for two-dimensional use. Two-dimensional slots 206 are providedfor no-back-bend use. Rectangular recesses 208 are provided forthree-dimensional use.

When the projections of a link are inserted in the recesses of themating link which have respective characteristic features, the movablerange of the projections is restricted, and link motions conforming tothe desired purpose can be performed.

The links are interchangeable and can be interconnected as desired.Therefore, recoupling of the links to conform to a given purpose can beeasily carried out in situ.

In addition, the tips of the projections are so set as to touch thebottoms of the recesses lightly in a loose fitting manner. Articulationof the links therefore takes place smoothly. Since the projections areinserted and engaged in recesses, the links are resistant to slippingapart under load.

Links 200 can be used in a one-dimensional manner by insertion of anannular spacer between adjacent links, and providing at least oneprojection (pin) in addition to the opposed pair of projections 210(FIG. 62C) by driving the pin or pins into a drilled hole or holes.However, the links 126 as they are can cope with two-dimensional andthree-dimensional motions.

In order to change the characteristics of the engaged links by rotatingthe links, passages 212 may be provided conforming to the widths of theprojections so that the projections can be moved between the recesses.With this arrangement, each projection engaged with a given recess canbe easily engaged to another recess suitable for the purpose, byslightly rotating the links while maintaining the connection of thelinks.

The relationship between the projections and the recesses which areprovided respectively on the concave spherical surface side and theconvex spherical surface sides in the figures, may be reversed.

The links of the sheath can be composed of various materials includingmetals. However synthetic polymers are preferred for most applications.

In addition, the link shapes shown in the figures are merely specificexamples, and various modifications can be made, such as described withreference to the other embodiments described herein.

We claim:
 1. A flexible supporting sheath for cables and the likecomprising a series of interconnected links, each link having aninternal passage extending through it form one end to the other, saidinternal passage having circular transverse cross-sections throughoutits length, an inner concave spherical surface formed in the passage atone end of the link, and an outer convex spherical surface formed on theouter surface of the link at its opposite end, in which, for at leasttwo adjoining links of the sheath, the convex surface of one of said twolinks is engaged with a concave surface of the other one of said twolinks, in which the engaged convex and concave surfaces havingcoinciding centers, and in which the concave surface of said other linkoverlaps the convex surface of said one link to an extent such as toprevent separation of the links, said two adjoining links having meansfor limiting their articulation, the internal passage of each of saidtwo links having an intermediate portion located between the concavesurface of its passage and the end portion of the passage inside theportion of the link having the outer convex surface, characterized bythe fact that the diameter of said end portion of the passage of saidone link, at its opening, is greater than the minimum diameter of theintermediate portion of the passage of said other link, whereby said twolinks form a continuous hollow passage for a cable or the like, saidpair of mating concave and convex spherical surfaces being provided withat least one set of aligned radial holes and having a pin extending atleast partly into both holes of at least one set, the pin being pressfit into one hole of the set and fitting loosely in the other hole ofthe set.
 2. A flexible supporting sheath according to claim 1 whereinsaid two adjoining links have outer surfaces having a gap between them,wherein said means for limiting articulation comprises a spacer locatedin said gap, and having connecting means, unitary with said pin andspacer, for connecting said pin to said spacer.
 3. A flexible supportingsheath according to claim 2 in which said one set of radial holes arealigned along an axis of articulation of said two adjoining links, an inwhich said means for preventing articulation of said two adjoining linksin a first direction, permits articulation of said two adjoining linksin a second direction opposite to said first direction.
 4. A flexiblesupporting sheath according to claim 1 in which said pair of matingconcave and convex spherical surfaces are provided with a second set ofaligned radial holes, in which the aligned radial holes of said one setand the aligned radial holes of said second set are aligned respectivelyalong two different axes, whereby, by the insertion of an additional pinthrough both radial holes of said second set, said two adjoining linkscan be fixed against articulation relative to each other.
 5. A flexiblesupporting sheath according to claim 4 in which said two different axesintersect.
 6. A flexible supporting sheath according to claim 4 in whichsaid two different axes intersect perpendicularly.